I have my GeForce FX 5200 working under Myth and driving my 1080i RPTV monitor with a VGA cable. When I view 1080i native signals, things look pretty good. When I receive a 720p program and send it to the video card, it is scaled by the card and driver before being sent to the set as a 1080i signal. The result is a horrible, jaggy, motion-artifact laden mess.

The artifacts are at their worst in a football game. As the camera pans across nearly-horizontal lines you get this stairstep effect where sometimes gaps appear in the lines at regular intervals -- turning them into dashed lines. It's awful.

Am I missing something obvious in the settings for the driver? My modeline is locked to 1920x1080 interlaced (the only setting my TV accepts). The driver is version 6111 under Debian 2.4 kernel. MythTv is the application driving the card, and I'm using Xv (because of the numerous problems getting XvMC to work under Myth).

I really wonder if the artifacts/scaling are caused by the videocard/drivers. Video using 720p actually has a resolution of 1280x720 and 1080i has 1920x1080. Further 1080i has half the framerate of 720p because of the interlacing. First the video needs to be scaled to a higher resolution and further some tricks need to be done to get it interlaced. This can really introduce those artifacts and other issues. (the conversion further needs to happen VERY fast and needs a lot of cpu power)

I would really try to get XvMC working as it will speedup the stuff a lot and because of that might reduce the artifacts. If XvMC gives some other image problems try to use the X configuration option "XvmcUsesTextures".

Thanks for your response. This was not what I wanted to hear, as XvMC is pretty thoroughly broken in MythTv. The on screen display causes the system to freeze periodically, forcing a reboot of the X server to get things going again. The devs know about the problem but no one is currently working on it. It is generally felt that Xv gives superior image quality anyway, so the impetus to fix XvMC is lacking. Given that, is there anything that you can think of under Xv which might improve the quality of scaling from 720 to 1080 lines? It is really hampering my enjoyment of playoff games!